1. Field of the Invention
The present invention relates to new crystalline molecular sieve SSZ-63, a method for preparing SSZ-63 using N-cyclodecyl-N-methyl-pyrrolidinium cation as a structure directing agent and the use of SSZ-63 in catalysts for, e.g., hydrocarbon conversion reactions.
2. State of the Art
Because of their unique sieving characteristics, as well as their catalytic properties, crystalline molecular sieves and zeolites are especially useful in applications such as hydrocarbon conversion, gas drying and separation. Although many different crystalline molecular sieves have been disclosed, there is a continuing need for new zeolites with desirable properties for gas separation and drying, hydrocarbon and chemical conversions, and other applications. New zeolites may contain novel internal pore architectures, providing enhanced selectivities in these processes.
Crystalline aluminosilicates are usually prepared from aqueous reaction mixtures containing alkali or alkaline earth metal oxides, silica, and alumina. Crystalline borosilicates are usually prepared under similar reaction conditions except that boron is used in place of aluminum. By varying the synthesis conditions and the composition of the reaction mixture, different zeolites can often be formed.
The present invention is directed to a family of crystalline molecular sieves with unique properties, referred to herein as xe2x80x9cmolecular sieve SSZ-63xe2x80x9d or simply xe2x80x9cSSZ-63xe2x80x9d. Preferably, SSZ-63 is obtained in its silicate, aluminosilicate, titanosilicate, germanosilicate, vanadosilicate or borosilicate form. The term xe2x80x9csilicatexe2x80x9d refers to a molecular sieve having a high mole ratio of silicon oxide relative to aluminum oxide, preferably a mole ratio greater than 100, including molecular sieves comprised entirely of silicon oxide. As used herein, the term xe2x80x9caluminosilicatexe2x80x9d refers to a molecular sieve containing both alumina and silica and the term xe2x80x9cborosilicatexe2x80x9d refers to a molecular sieve containing oxides of both boron and silicon.
In accordance with this invention, there is provided an improved process for the reduction of oxides of nitrogen contained in a gas stream in the presence of oxygen wherein said process comprises contacting the gas stream with a zeolite, the improvement comprising using as the zeolite a zeolite having a mole ratio greater than about 15 of an oxide of a first tetravalent element to an oxide of a second tetravalent element different from said first tetravalent element, trivalent element, pentavalent element or mixture thereof and having, after calcination, the X-ray diffraction lines of Table II. The zeolite may contain a metal or metal ions (such as cobalt, copper or mixtures thereof) capable of catalyzing the reduction of the oxides of nitrogen, and may be conducted in the presence of a stoichiometric excess of oxygen. In a preferred embodiment, the gas stream is the exhaust stream of an internal combustion engine.